I managed to burn these for more than 30 hours now but to be honest I felt it had already opened up after the first 45 - 90 minutes of use. I could not tell any significant difference pass 12, 24 and now 30 hours into it.
I take any perceived slight improvements to be psychological or because I just love my music You can tell that I do have my reservations how much different it will sound past 300 hours but I will wait for that and see
At the moment, with a 3.5mm splitter cable, I am comparing the Sony MH1C with Superlux HD381F since I got both at the almost identical price at around USD$20.
HD381F was mentioned as a good value performer (I believe it still is, for the price) giving very good tonal balance with a slight forward midrange. There is a thread that even compared them to other higher end IEMs like TF10, Shure SE530, Westone 3, UM3X, Audio Technica CK100 and the likes with HD381F somehow coming highly favourable to the TS.
Although I prefer the HD381B (its sibling) but many are more familiar with the HD381F, so I think I’ll throw it into the mix here as far as comparison goes.
First thing I noticed is that the MH1C needs to be driven slightly more to equal volume, but scales up a lot better than HD381F. MH1C seems more refined and takes more power to drive (the right technical term?) and treble top is smoother and everything notches up well with the volume control. At times I also feel that the MH1C feels more effortless whereas the HD381F is being stretched when compared to each other.
MH1C have more bass (from a good seal) giving a fuller bottom end which makes the overall presentation more immersive and enjoyable to me. However, male vocals of HD381F sound more present, raw and realistic than MH1C’s somehow too smooth signature though. For acoustic tracks, I find myself enjoying MH1C much more after EQing it to “Treble Booster” using iTunes.
I took that recommendation from someone here in this thread but I can’t remember exactly who. I think this EQ somehow works very well with MH1C and could easily become my favourite tuning. It kinda takes the veil off that smoothness (if that made any sense) and bring back the energy/life at the highs that I like.
The HD381F is vented and will sound more open and appears to convey live tracks much better. MH1C still have a better soundstage depth to my ears though, and I think it’s because the midrange of HD381F is slightly more forward. HD381F seems to be slightly better at vocal timbre and presence.
Soundstage width is about the same, both still appearing in-your-head and narrow as with most IEMs. Imaging placement is slightly better with MH1C. Instruments can sound less separated and more congested on HD381F.
Microphonic is a black and white thing to me. I do not tolerate microphonics well. It’s almost impossible for me to take the MH1C out for a walk as it proved to be too microphonic for me, even with the shirt clip on. I never had any problem with HD381F though. Having said that, the seal with MH1C is better but at a stationary position. I guess the MH1C will be fixed to home use for me.
Before I get flamed or killed lol, I want to clarify that I’m not saying MH1C is the best IEM ever or anything like that. I am also not indicating that they are very good at the highest level. Most likely and I am very sure that they are not. I use the word ‘slightly’ to indicate that the difference is not drastic and may not be immediately noticeable at casual listening. I am just comparing between these two IEM at the same price and how it sounds to me. Thats all. These descriptions are my subjective take, so please take with a grain of salt. Peace guys!